IN THIS ISSUE
Summary: This Review article examines the role of heparan sulfate proteoglycans in vertebrate development and explores the concept of an instructive 'sugar code' for modulating development.
STEM CELLS AND REGENERATION
Dynamic transcriptional symmetry-breaking in pre-implantation mammalian embryo development revealed by single-cell RNA-seq
Highlighted article: Partitioning errors in the zygote, modulated by embryonic transcription, give rise to the unequal distribution of lineage specifiers between blastomeres that subsequently drives lineage specification.
Lin-28 promotes symmetric stem cell division and drives adaptive growth in the adult Drosophila intestine
Highlighted article: Lin-28 boosts insulin signaling in adult Drosophila intestinal progenitors in response to nutrients, adjusting the rate of symmetric renewal of stem cells and driving intestinal tissue growth.
Summary: LIF, the cytokine central for ESC self-renewal, supports heterogeneous mouse ESC cultures and early embryo development by stimulating primitive endoderm expansion and paracrine loops, and by blocking epiblast differentiation.
Summary: The chromatin modifier Trithorax regulates a negative feedback loop that controls JNK signaling and Insulin-like Peptide 8 expression in damaged Drosophila imaginal discs.
Summary: Robo2 is required in tendons to restrict Slit distribution by promoting its cleavage into a non-diffusible Slit-N, affecting muscle elongation towards tendons in Drosophila embryos.
Highlighted article: Mouse thyroid C cell precursors arise in foregut endoderm, and not the neural crest, disproving the current concept of a neural crest origin of thyroid neuroendocrine cells.
Highlighted article: Levels of histone H3 methylation and acetylation control the expression of Atoh1, a key regulator of hair cell differentiation, during inner ear development in mice.
Summary: The ATP-binding cassette (ABC) transporter ABCC5 transports cAMP from mesoderm cells to control late invagination of the sea urchin hindgut, revealing a novel developmental role for an ABC transporter.
Polarized Rac-dependent protrusions drive epithelial intercalation in the embryonic epidermis of C. elegans
Summary: Basolateral protrusive activity, and not apical constriction, drives cell intercalation in C. elegans embryos and is regulated by Rac/RhoG and WAVE/WASP.
Allorecognition, via TgrB1 and TgrC1, mediates the transition from unicellularity to multicellularity in the social amoeba Dictyostelium discoideum
Summary: TgrB1 and TgrC1 - the molecules that mediate allorecognition in D. discoideum - also control the integration of individual cells into a unified developing organism, acting as a gating step for multicellularity.
A germ cell determinant reveals parallel pathways for germ line development in Caenorhabditis elegans
Summary: The chromatin-associated protein XND-1 is identified as a key regulator of a novel pathway for primordial germ cell differentiation in C. elegans.
TECHNIQUES AND RESOURCES
Summary: This comprehensive developmental dataset, which combines optical projection tomography and image registration methods, provides a new and powerful staging system for mouse embryos.
Summary: This methodology permits long-term imaging and tracking of NSCs in the adult zebrafish telencephalic neurogenic niche, allowing the frequency, distribution and modes of NSC divisions to be analyzed.
Tracking and transforming neocortical progenitors by CRISPR/Cas9 gene targeting and piggyBac transposase lineage labeling
Summary: The CRISPR/Cas9 system is used to target three tumor suppressor genes (PTEN, NF1 and P53), alone and in combination with piggyBac transposase lineage marking, to analyze their function in the developing mouse brain.